In this example, we will grade from a size 38 at the waist to a size 40 at the hips. Start by tracing pieces #6 to #10 (single size), then pieces #4 and #5 (waistband) in size 38.
The side stripes should stay straight, so trace piece #3 according to your hip size (here 40) for the width, and waist size (here 38) for the height.
For piece #2 (back leg), we’ll grade from a size 38 to 40. Start by tracing size 38 at the top of the back leg (dart included), then grade progressively to reach size 40 at the hip double-notch (on the outside) and the crotch cuve (on the inside). IMPORTANT: you’ll then need to remove some width from the top right of the back leg, corresponding to the ungraded amount on the side stripe, i.e. 2.5 mm per size!
Do the same for the front leg piece (#1): grade the outside from the top of the piece to the hip notch, and the inside from the bottom of the fly to the crotch curve. Don’t forget to remove 2.5 mm per size from the top left of the piece as well!